V4 sti knock sensor earthed

[garyf]

Car is a v4 sti with the single wire knock sensor, Ive got an s6 pnp with no knock control.

Ive had a missfire for a couple of months now, Ive redone my coil packs loom, replaced all coil packs and spark plugs, this made no difference.

Its sort of coming and going, itll be 1.02 on lambda when warm and be 1.3 on low load with a definite miss. Then one day itll almost be ok, Ill drive for 10 mls and itll just start missing when at the end of the journey then itll miss for 2 weeks. Ive had the injectors checked and they are ok but wont get them back until tomorrow.

I removed the engine loom tonight so I could rewire each injector and its earth before I get the injectors back and I found a broken wire. Its broken on the knock sensor plug right at the plug and it looks like the freyed wire has been earthing on the block. its not throwing any errors on syvecs, I have had about 3 engine trips saying 109 I think, its 3 weeks ago now and ive been offshore. Would this wire earthing mess up fueling?

[stevieturbo]

not a wonder it's missing if mixtures are 1.3 lambda, that's mega weak.

If knock sensor is suspect ( unlikely it will cause any mixture changes )...just turn it off in I/O

[garyf]

I know itll miss at 1.3, thats not what Im asking. I want to know if the sensor is grounding will it cause this effect on fueling? Its missing at idle at 1.02 today, tomorrow itll be 0.95 and be fine and drive normally.

The injectors are away being checked and are ok, I get them back next week, in the mean time I decided to check the engine loom and found the shorted wire. A grounded sensor wire cant be good so I was wondering if it would affect the afr. Ive buzzed through the ignition and injector wiring and its ok, but Ive rewired both today to be sure there isnt any issues. Ive tried putting in 30% more fuel and it makes little difference.

Just have to wait and see if its better when i get the injectors back, the knock sensor issue is repaired now.

[stevieturbo]

The knock sensor should not affect fueling.

If you have wiring issues that may affect other wiring in the system, then possibly that could. But as knock sensors is only a signal and sensor ground......it should be independent of all else, unless someone has wired it wrong to begin with

Has it ever been tuned correctly and ran correctly ?

[TimH]

Its not throwing any errors on syvecs, I have had about 3 engine trips saying 109 I think, its 3 weeks ago now

109 is VVT fail (again, perhaps a wiring issue?) and that would be logged as an error, although possibly just in yellow to show historic rather than red to show current.

Given the injector wiring fault, VVT fail (probably wiring) and knock sensor issue it's probably time to seek out a replacement engine loom!

[garyf]

The knock sensor should not affect fueling.

If you have wiring issues that may affect other wiring in the system, then possibly that could. But as knock sensors is only a signal and sensor ground......it should be independent of all else, unless someone has wired it wrong to begin with

Has it ever been tuned correctly and ran correctly ?

It was running well until around feb - march, I fitted cams last august and on starting there was always a very slight miss until warm, I put this down to the cams being reasonable aggressive, possibly they were just showing up the beginings of this fault. Knock sensor was working also since its showing appropriate values in my old logs.

[garyf]

Its not throwing any errors on syvecs, I have had about 3 engine trips saying 109 I think, its 3 weeks ago now

109 is VVT fail (again, perhaps a wiring issue?) and that would be logged as an error, although possibly just in yellow to show historic rather than red to show current.

Given the injector wiring fault, VVT fail (probably wiring) and knock sensor issue it's probably time to seek out a replacement engine loom!

Ok thats makes sense on the vvt, I have a seperate loom for the vvt, one of the wires at the solenoid plug was broken one day due to me having been poking about looking for this fault, I just solderd in a new plug. Ive redone the seperate loom I have for coil packs, so wires and plugs and your tails so thats good. Also replaced the injector plugs for new and rewired back to the big plug on the ns, did the 2 coil pack signal feeds too and their 12v supply.

Ill order some smaller gauge wire with appropriate sensor plugs and do all the sensor feeds back to the big plug also, just need my injectors back, DPD have lost them! I have another engine loom but it seems as crusty as mine. Gona have a good look at the ecu side this afternoon to see if theres anything obvious there.

[garyf]

I got the injectors back on monday and it was still the same, Ive just been checking wires since and I havnt found anything. I took the car out today and did a log from cold, It started to almost run cleanly by 3 miles, the logs looked ok , vvt working and no sensor spikes. I took it out tonight again and it went lean at the end of the run, you can see it clearly at the log end at 20:34:10, tried the same rpm and map and the afr was normal, I dont think its an ignition signal wire it didnt feel too bad, any thoughts? Is it an injector going downs.

[garyf]

One other thing, I updated firmware and syvecs suite, when I try to connect to the ecu now it cant find it until Ive installed the suite, itll connect a couple of hours later, if I try to connect again the next day itll need reinstalled again?

[stevieturbo]

I've had the same connections issues since last update.

No idea why, sometimes on bootup it will find an ecu, others it wont. I keep the SSuite file on the desktop now for quick re-install when it happens